Conventional heat exchangers have a plurality of flat tubes arranged one above the other, fins joined to the flat tubes, and two header collecting pipes each connected to one or the other end of the plurality of flat tubes, and are configured to exchange heat between a refrigerant and air (see, e.g., Patent Document 1 shown below).
In such a heat exchanger, a plurality of communication spaces, which communicate with associated ones of the plurality of flat tubes, are formed in each of the header collecting pipes. In this heat exchanger, the refrigerant which has flowed into the respective communication spaces is distributed into the plurality of flat tubes arranged one above the other in the communication space, and exchanges heat with the air while flowing through the respective flat tubes.